WO2019230520A1

WO2019230520A1 - Abnormality diagnosis system and vibration sensor

Info

Publication number: WO2019230520A1
Application number: PCT/JP2019/020277
Authority: WO
Inventors: 公司生田; 具也市村; 義広遠藤; 愛林劉
Original assignee: 光洋電子工業株式会社
Priority date: 2018-05-28
Filing date: 2019-05-22
Publication date: 2019-12-05
Also published as: JP2019207126A

Abstract

Provided are an abnormality diagnosis system and a vibration sensor that can detect an abnormality occurring in a device while suppressing frequency analysis errors even when a sampling interval of vibration acceleration by a vibration sensor fluctuates depending on the individual difference or use temperature environment. An abnormality diagnosis system 1 is provided with: a sensor 2 that is attached to a device 6 to be diagnosed and that periodically detects vibration acceleration and measures the time interval of the acceleration detection; a spectrum analysis means 32 for executing spectrum analysis for the acceleration on the basis of the detection value of the acceleration detected by the sensor 2 and the time interval; and an abnormality detection means for detecting an abnormality of the device 6 on the basis of a spectrum for each frequency acquired by the spectrum analysis means 32.

Description

Abnormality diagnosis system and vibration sensor

The present invention relates to an abnormality diagnosis system for diagnosing abnormality of a device based on an analysis result of vibration generated in the device, and a vibration sensor used for the abnormality diagnosis system.

Conventionally, an abnormality diagnosis device that diagnoses an abnormality of a device based on an analysis result of vibration generated in the device is known (see, for example, Patent Document 1).

An abnormality diagnosis apparatus (evaluation apparatus) described in Patent Document 1 includes a vibration detection unit that outputs an analog signal of sound or vibration generated from mechanical equipment, an amplification unit that amplifies the analog signal output by the vibration detection unit, and an amplification AD conversion means for converting the analog signal amplified by the means into a digital signal, and frequency analysis is performed on the output of the AD conversion means to generate measured frequency spectrum data, and it is generated due to an abnormality in the mechanical equipment Arithmetic processing means for diagnosing whether there is an abnormality in the mechanical equipment based on the presence / absence of a peak on the measured frequency spectrum data with respect to the primary value, the secondary value, and the quaternary value of the frequency component.

Japanese Patent Laid-Open No. 2003-130763

As a sensor for realizing the vibration detecting means, the amplifying means, and the AD converting means, generally, a piezoelectric element type accelerometer, each of which is individually unitized, is used.

On the other hand, in recent years, a digital output type MEMS acceleration IC (hereinafter simply referred to as an “acceleration sensor IC”) integrated with a function of measuring, quantifying and digitally outputting vibration acceleration due to advances in semiconductor MEMS (Micro Electro Mechanical Systems) technology. ) Can be obtained at a low cost, and can be manufactured at a lower cost than a piezoelectric element type accelerometer.

In frequency analysis, for example, FFT (Fast Fourier Transform) is performed based on data sampled every fixed time interval T seconds, and the inverse of the fixed time interval T is called ODR (Output Data Rate). It represents the quantity of data output per second, and is a performance index that enables measurement up to a high frequency region as the value increases. The ODR of an inexpensive acceleration sensor IC has a characteristic variation for each individual and also varies depending on the operating temperature environment. If the ODR set in the acceleration sensor IC is different from the actual ODR, an error is generated in the analysis result because the calculation is performed with the set ODR in the frequency analysis.

Therefore, the present invention provides an abnormality diagnosis capable of detecting an abnormality occurring in a device while suppressing an error in frequency analysis even if the sampling interval of vibration acceleration by the vibration sensor varies depending on individual differences or operating temperature environment. It is an object to provide a system and a vibration sensor used therefor.

In order to achieve the above-mentioned object, the present invention is an abnormality diagnosis system for diagnosing abnormality of a device by measuring vibration generated in the device to be diagnosed, which is attached to the device and periodically determines acceleration of vibration. A vibration sensor for measuring a time interval at which the acceleration is detected, a spectrum analysis means for spectrally analyzing the acceleration based on the detected value of the acceleration detected by the vibration sensor and the time interval, There is provided an abnormality diagnosis system having abnormality detection means for detecting an abnormality of the device based on a spectrum for each frequency obtained by a spectrum analysis means.

Further, in order to achieve the above object, the present invention provides a vibration sensor that is attached to a device to be diagnosed and periodically detects the acceleration of vibration and measures the time interval at which the acceleration is detected.

According to the abnormality diagnosis system and the vibration sensor according to the present invention, even if the sampling interval of vibration acceleration by the vibration sensor fluctuates due to individual differences or operating temperature environment, an error occurring in the device is detected by suppressing frequency analysis error. It becomes possible to do.

It is a schematic block diagram which shows the abnormality diagnosis system which concerns on embodiment of this invention with the programmable controller which controls the apparatus of diagnosis object, and an apparatus. It is a block diagram which shows the structural example of a sensor part. It is a figure which shows an example of the transmission data which a sensor part outputs. It is a figure for demonstrating the acceleration which acceleration sensor IC detects. It is a figure which shows the transmission data sequentially written in a transmission buffer. It is a flowchart which shows the main process routine of CPU of a sensor part. It is a flowchart which shows the CPU interruption process routine of a sensor part.

[Embodiment]
Embodiments of the present invention will be described with reference to FIGS. In addition, although embodiment described below is shown as a suitable specific example in implementing this invention, although there are some parts which have illustrated various technical matters that are technically preferable. The technical scope of the present invention is not limited to this specific embodiment.

FIG. 1 is a schematic configuration diagram showing an abnormality diagnosis system 1 according to an embodiment of the present invention, together with a device 6 to be diagnosed and a programmable controller 7 that controls the device 6. The abnormality diagnosis system 1 diagnoses an abnormality of the device 6 by measuring vibration generated in the device 6.

The abnormality diagnosis system 1 includes a sensor unit 2 attached to the device 6, a logger unit 3 that acquires and stores transmission data 200 (see FIG. 3) transmitted from the sensor unit 2, and a computer connected to the logger unit 3. 4.

The device 6 is a machine tool that performs predetermined machining and assembly on a workpiece in a predetermined cycle time, for example, and the electric motor 61, the movable portion 62 driven by the electric motor 61, and the operation of the movable portion 62. A rolling bearing 63 and the like for smoothness are included. The sensor unit 2 is fixed to the electric motor 61 and the movable unit 62 of the device 6 configured as described above or the vicinity thereof by bolts or the like.

The sensor unit 2 periodically detects the acceleration of vibration, detects the temperature, measures the time interval at which the acceleration is detected, and transmits these as transmission data 200 to the logger unit 3. Details of the sensor unit 2 will be described later.

The logger unit 3 is connected to the sensor unit 2 through the serial communication line 25d, and receives the transmission data 200 from the sensor unit 2 through serial communication via the serial communication line 25d. The logger unit 3 includes a CPU (arithmetic processing unit) and a storage unit such as a ROM and a RAM. The CPU executes a program stored in the storage unit, whereby a data storage unit 31, a spectrum analysis unit 32, It functions as an abnormality determination means 33, an abnormality signal output means 34, and the like. The abnormality determination unit 33 and the abnormality signal output unit 34 are examples of an abnormality detection unit.

The data storage unit 31 is a unit that stores the transmission data 200 received from the sensor unit 2 in the storage unit.

The spectrum analysis unit 32 is a unit that performs spectrum analysis on the acceleration data included in the transmission data 200 transmitted from the sensor unit 2. More specifically, the spectrum analysis unit 32 performs an FFT operation on the acceleration data of the sensor unit 2 stored in the storage unit by the data storage unit 31 and calculates the intensity (acceleration) of vibration for each frequency. The FFT calculation by the spectrum analysis unit 32 will be described later.

The abnormality determination means 33 is a means for determining that an abnormality has occurred in the device 6 when the spectrum analysis result obtained by the spectrum analysis means 32 exceeds a threshold set by the computer 4 described later at any frequency. is there.

The abnormality signal output means 34 is a means for outputting an abnormality signal indicating the occurrence of the abnormality when the abnormality determination means 33 determines that an abnormality has occurred in the device 6.

The computer 4 is connected to the logger unit 3 by, for example, a wireless LAN or a communication line, and can perform bidirectional communication with the logger unit 3. The computer 4 functions as a peak value extraction unit 41, a threshold setting unit 42, and the like when the CPU executes a program stored in advance in a hard disk or the like.

The peak value extraction means 41 extracts the peak value of the spectrum for each frequency obtained by the spectrum analysis means 32. Here, the “peak value” is the maximum value of the vibration intensity at the frequency in the spectrum analysis result over a predetermined period. The threshold setting unit 42 sets a threshold value for determining an abnormality based on the peak value for each frequency extracted by the peak value extracting unit 41. The set threshold value is transmitted to the logger unit 3, and the logger unit 3 stores this threshold value.

In this embodiment, the threshold setting unit 42 sets a value obtained by adding a predetermined value to the peak value for each frequency extracted by the peak value extracting unit 41 as a threshold. If this predetermined value is small, erroneous detection of abnormality frequently occurs, and if it is too large, the abnormality cannot be detected even if an abnormality has occurred. Therefore, this predetermined value is set to a value that does not cause the vibration intensity to exceed the threshold value when the device 6 is normal and can reliably detect the occurrence of the abnormality when the abnormality occurs.

Further, a display device 51 is connected to the computer 4, and is set by the analysis result by the spectrum analysis unit 32, the information of the detection value of the sensor unit 2 stored by the data storage unit 31, and the threshold setting unit 42. The threshold value information can be displayed on the display screen and presented to the user. The user can edit the threshold value by operating the input device 52 (a pointing device such as a keyboard or a mouse) of the computer 4. When the threshold set by the threshold setting means 42 is edited by the user, the edited threshold information is transmitted to the logger unit 3 and stored.

FIG. 2 is a block diagram illustrating a schematic configuration example of the sensor unit 2. The sensor unit 2 includes an acceleration sensor IC (Integrated Circuit) 21, a temperature sensor IC 22, a CPU 23, a time difference measurement counter 24, and a communication driver IC 25.

The acceleration sensor IC 21 is a digital output type MEMS sensor that detects vibration acceleration with a set ODR (for example, 3200 Hz) and digitally outputs a detection value corresponding to the detected vibration intensity (acceleration). That is, the acceleration sensor IC 21 includes a detection unit that simultaneously detects accelerations in three directions perpendicular to each other (X direction, Y direction, and Z direction) and a digital output unit that outputs detection values of acceleration as digital data (acceleration data). It is integrally formed by technology. The acceleration sensor IC21 detects acceleration in synchronization with the clock signal CLK transmitted from the CPU 23 via the clock line 21a, and detects the detected acceleration value as digital data (acceleration data) to the CPU 23 via the data line 21b. Send. The acceleration sensor IC 21 transmits an interrupt signal Si to the CPU 23 via the interrupt line 21c every time it detects acceleration.

The temperature sensor IC 22 detects the temperature in synchronization with the clock signal CLK transmitted from the CPU 23 via the clock line 22a, and transmits the detected temperature to the CPU 23 via the data line 22b as digital data (temperature data).

The CPU 23 includes a transmission data creating unit 230 that creates the transmission data 200 and a transmission buffer 231 in which the transmission data 200 is written. The CPU 23 functions as the transmission data creation unit 230 and the like by executing a program stored in a storage unit (not shown) such as a ROM or a RAM.

The transmission data creating means 230 is synchronized with the clock signal CLK, the acceleration data 202 to 204 transmitted from the acceleration sensor IC 21, the temperature data 205 transmitted from the temperature sensor IC 22, and the time based on the count value acquired from the time difference measurement counter 24. Transmission data 200 (see FIG. 3) including data 206 and header 201 is created.

The time difference measurement counter 24 counts the reference clock signal bCLK transmitted from the CPU 23 via the clock line 24a, and outputs a count value to the data bus 24c based on the data read signal transmitted via the signal line 24d. The count value is reset by the count reset signal CRS transmitted from the CPU 23 via the count reset signal line 24b. The time difference measurement counter 24 may be provided in the CPU 23.

The communication driver IC 25 receives the transmission data 200 from the transmission buffer 230 of the CPU 23 via the transmission line 25a. When a command indicating a sampling command is sent from the logger unit 3 side, the communication driver IC 25 transmits the command to the CPU 23 via the reception line 25b. The communication driver IC 25 transmits information of the transmission line 25a or the reception line 25b used from the CPU 23 via the control line 25c. The communication driver IC 25 transmits the transmission data 200 to the logger unit 3 via the serial communication line 25d.

FIG. 3 is a diagram illustrating an example of the data format of the transmission data 200. As shown in FIG. 3, the transmission data 200 includes a header 201 indicating the head of the transmission data 200, X-axis acceleration data 202, Y-axis acceleration data 203 and Z-axis acceleration data 204 as detected acceleration values, and temperature data. 205 and time data 206 are included. Here, the time data 206 is an example of a time interval. The header 201 is composed of 1 byte, and the other data 202 to 206 are composed of 2 bytes.

The transmission data creation means 230 receives the X-axis acceleration data 202, the Y-axis acceleration data 203, and the Z-axis acceleration data 204 as detected values of the X-axis, Y-axis, and X-axis accelerations transmitted from the acceleration sensor IC21. Then, the temperature data 205 as the detected temperature value transmitted from the temperature sensor IC 22 is received, the counter value output from the time difference measurement counter 24 is acquired as the time data 206, and the header 201 is added to these data 202 to 206. In addition, transmission data 200 is created.

FIG. 4 is a diagram for explaining the acceleration detected by the acceleration sensor IC21. The figure shows the detected value of acceleration in the X-axis direction. The acceleration sensor IC 21 detects acceleration (X-axis acceleration in FIG. 4) at a predetermined sampling interval. The sampling interval is measured by the count value of the reference clock bCLK by the time difference measurement counter 24. The acceleration sensor IC 21 samples, for example, X-axis acceleration data (n), X-axis acceleration data (n + 1),... At a constant cycle such as about 3200 times / second. The ODR that is the reciprocal of the sampling interval varies depending on individual differences and ambient temperature due to performance variations of the clock circuit and the like due to the manufacturing process of the acceleration sensor IC21. For this reason, if a frequency analysis is performed with a preset ODR, an error occurs. Therefore, in this embodiment, the sampling interval is measured by counting the reference clock signal bCLK.

FIG. 5 is a diagram showing transmission data 200 sequentially written in the transmission buffer 231. At a certain detection timing, acceleration data 202 to 204 including the X axis (n), Y axis (n), and Z axis (n), temperature data 205 of temperature (n), and time data 206 based on the counter value (n). The transmission data 200 including the header 201 is generated by the transmission data generation unit 230, and the transmission data 200 is written in the transmission buffer 231. At the next timing, acceleration data 202 to 204 composed of X axis (n + 1), Y axis (n + 1), and Z axis (n + 1), temperature data 205 of temperature (n + 1), and time data 206 based on counter value (n + 1). The transmission data 200 including the header 201 is generated by the transmission data generation unit 230, and the transmission data 200 is written in the transmission buffer 231. In this way, the transmission data 200 is sequentially created and overwritten in the transmission buffer 231. That is, the transmission data creating unit 230 creates the transmission data 200 every time the interrupt signal Si is transmitted from the acceleration sensor IC 21, and writes the transmission data 200 in the transmission buffer 231. The transmission data 200 written in the transmission buffer 231 is sequentially transmitted to the logger unit 3 by the communication driver IC 25.

In the FFT calculation by the spectrum analysis unit 32, time data 206 included in a predetermined number (eg, 1024) of transmission data 200 is averaged, and the average value is used as the sampling interval for the FFT calculation. As a result, even if the sampling interval varies due to individual differences of the acceleration sensor IC 21 or the ambient temperature environment, the influence can be suppressed and the frequency analysis can be performed.

(Operation of sensor unit 2)
Next, the operation of the sensor unit 2 will be described with reference to the flowcharts of FIGS.

FIG. 6 is a flowchart showing an example of the main processing routine of the CPU 23. First, the CPU 23 executes a command processing routine. That is, after setting the 1-second timer (S1), it is determined whether or not a command is input (S2). If a command is input (S2: Yes), the command is processed (S3). Whether or not a command has been input is determined until the one-second timer expires (S4: Yes).

When the 1-second timer expires (S4: Yes), the CPU 23 executes a data transmission processing routine.

In the data transmission processing routine, the data flag is checked (S5). When the data flag is “1”, acceleration data 202 to 204 output from the acceleration sensor IC 21, temperature data 205 output from the temperature sensor IC 22, time data 206 based on the count value acquired from the time difference measurement counter 24, and The transmission data 200 is created from the header 201, the transmission data 200 is set in the transmission buffer 230, the transmission data is transmitted to the communication driver IC 25 (S6), and the data flag is set to “0” (S7).

FIG. 7 is a flowchart showing an example of the interrupt processing routine of the CPU 23. When the interrupt signal Si is transmitted from the acceleration sensor IC 21 via the interrupt line 21c, the CPU 23 reads the acceleration data (S11), reads the temperature data (S12), reads the counter value (S13), and then the counter The value is cleared (S14), and the data flag is set to “1” (S15).

(Abnormal diagnosis method)
Next, an abnormality diagnosis method in the abnormality diagnosis system 1 will be described.

This abnormality diagnosis method includes a preparation process that is a preparation stage of diagnosis and a diagnosis process that diagnoses the device 6 after the preparation process is completed. In the preparation process, the acceleration data acquired from the sensor unit 2 is subjected to spectrum analysis, the peak value of the spectrum for each frequency obtained by the spectrum analysis is extracted, and an abnormality is determined based on the extracted peak value for each frequency. Set the threshold.

The diagnostic process performs a spectrum analysis on the acceleration data acquired from the sensor unit 2 and determines whether or not an abnormality has occurred in the device 6 by comparing the analyzed spectrum analysis result with the threshold value set in the threshold setting. When it is determined that an abnormality has occurred in the device 6, a signal indicating the occurrence of the abnormality is output. In the abnormality determination, when the spectrum analysis result exceeds a threshold value at any frequency, it is determined that an abnormality has occurred in the device 6.

In order to prevent erroneous detection of an abnormality in the device 6, it is desirable to set a threshold value based on the result of measuring vibration over a cycle time of 1000 times or 10,000 times, for example. Further, when a sensor unit 2 capable of detecting vibration intensities in three directions perpendicular to each other is used, the same diagnosis is performed for each of these three directions. Furthermore, when a plurality of sensor units 2 are attached to the device 6, the same diagnosis as described above is performed for each of the plurality of sensor units 2.

As described above, the abnormality determination means 33 determines that an abnormality has occurred in the device 6 when the spectrum analysis result exceeds the threshold set by the threshold setting at any frequency. Such an abnormality can occur, for example, due to wear of the rolling bearing 63, damage to the gears in the movable portion 62, or excessive wear or breakage of the cutting tool. When it is determined that an abnormality has occurred in the device 6, the abnormality signal output means 34 outputs an abnormality signal indicating the occurrence of the abnormality. Specifically, an abnormal signal is output from the logger unit 3 to the programmable controller 7 by the processing of the abnormal signal output means 34.

The alarm device 8 is connected to the programmable controller 7. The alarm device 8 notifies an operator of the occurrence of an abnormality, and is, for example, a lamp or a buzzer. The programmable controller 7 stores in advance a sequence program constructed so as to activate the alarm device 8 when an abnormal signal is received from the logger unit 3. Moreover, the programmable controller 7 stops control of the apparatus 6 as needed, when an abnormal signal is received from the logger part 3. FIG.

(Operation and effect of the embodiment)
According to the embodiment described above, the acceleration sensor IC 21 periodically detects the acceleration of vibration, measures the time interval at which the acceleration is detected, and sets the detected acceleration value and time interval detected by the acceleration sensor IC 21. Based on the spectrum analysis of the acceleration based on this, even if the time difference of the individual differences of the acceleration sensor IC21 varies depending on the ambient environment temperature, the error of the spectrum analysis can be suppressed. As a result, an abnormality occurring in the device 6 can be detected. That is, when the spectrum analysis result exceeds a threshold value at any frequency, it is determined that an abnormality has occurred in the device 6. It is possible to detect various abnormalities occurring in the device 6.

(Appendix)
As described above, the abnormality diagnosis system and abnormality diagnosis method of the present invention have been described based on the embodiments. However, the present invention is not limited to the above embodiments, and can be implemented in various modes without departing from the scope of the present invention. Is possible. For example, in the above-described embodiment, the case where the device 6 is a machine tool has been described. However, the present invention is not limited to this, and various devices can be diagnosed. In the above embodiment, the time data is transmitted to the logger unit as transmission data together with the detection data (acceleration data, temperature data). However, the time data may be transmitted to the logger unit separately from the detection data. Moreover, it is good also as only acceleration data as detection data transmitted with time data.

The present invention can be applied to a machine tool or the like that performs predetermined machining or assembly on a workpiece.

DESCRIPTION OF SYMBOLS 1 ... Abnormality diagnosis system 2 ... Sensor part 3 ... Logger part 4 ... Computer 6 ... Equipment 21 ... Acceleration sensor IC
22 ... Temperature sensor IC
23 ... CPU
24 ... Time difference measurement counter 25 ... Communication driver IC
31 ... Data storage means 32 ... Spectrum analysis means 33 ... Abnormality determination means 34 ... Abnormal signal output means 41 ... Peak value extraction means 42 ... Threshold setting means 200 ... Transmission data 230 ... Transmission data creation means 231 ... Transmission buffer bCLK ... Reference clock Signal CRS ... Counter reset signal CLK ... Clock signal Si ... Interrupt signal

Claims

An abnormality diagnosis system for diagnosing abnormality of the device by measuring vibration generated in the device to be diagnosed,
A vibration sensor attached to the device for periodically detecting acceleration of vibration and measuring a time interval at which the acceleration is detected;
Spectrum analysis means for spectrally analyzing the acceleration based on the detected value of the acceleration detected by the vibration sensor and the time interval;
An abnormality detection means for detecting an abnormality of the device based on a spectrum for each frequency obtained by the spectrum analysis means;
An abnormality diagnosis system having
The abnormality diagnosis system according to claim 1, wherein the spectrum analysis means performs spectrum analysis of the vibration at a sampling interval obtained by averaging a predetermined number of the time intervals.
The abnormality diagnosis system according to claim 1 or 2, wherein the vibration sensor outputs transmission data including the detected value of the acceleration and the time interval to the spectrum analyzing means.
The vibration sensor detects the temperature of the device at the same timing as the acceleration of the vibration, and outputs transmission data including the detected value of the temperature, the detected value of the acceleration, and the time interval to the spectrum analyzing unit. The abnormality diagnosis system according to claim 3.
The abnormality diagnosis system according to any one of claims 1 to 4, wherein the vibration sensor is a digital output type MEMS sensor that outputs the detection value as digital data.
The abnormality diagnosis system according to any one of claims 1 to 5, further comprising an output unit that outputs an abnormality signal indicating occurrence of a difference when a detected acceleration value exceeds a threshold value at any frequency. .
A vibration sensor that is attached to the device to be diagnosed and periodically detects the acceleration of vibration and measures the time interval at which the acceleration is detected.
The vibration sensor according to claim 7, wherein transmission data including the detected acceleration value and the time interval is output.
The vibration sensor according to claim 8, wherein the temperature of the device is detected at the same timing as the acceleration of the vibration, and transmission data including the detected value of the temperature, the detected value of the acceleration, and the time interval is output.
The vibration sensor according to claim 7, wherein the vibration sensor is a digital output type MEMS sensor that outputs the detection value as digital data.